Prosthesis and methods for unicompartmental and total knee arthroplasty

ABSTRACT

A knee joint prosthesis, comprising at least one femoral component and at least one tibial component. The femoral component having a first portion adapted for fixable attachment to a distal end of a femur and a second portion formed with a bearing surface. The femoral component is sized so as to permit attachment to the femur of a patient without severing at least one the cruciate ligaments. The tibial component has a first surface that is adapted to cooperate with a patient&#39;s tibia, while a second surface of the tibial component is adapted to cooperate with the femoral component. The tibial component is sized so as to permit attachment to the patient&#39;s tibia without severing at least one of the cruciate ligaments.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation patent application of, and claims priorityto, U.S. patent application Ser. No. 09/506,821, entitled “Methods andProsthesis for Total Knee Arthroplasty,” the disclosure of which isincorporated herein by this reference.

BACKGROUND OF THE INVENTION

[0002] 1. The Field of the Invention

[0003] The present invention relates to prosthetic structures andcorresponding surgical methods used to relieve pain caused by disordersof the knee joint. More particularly, the invention relates toprostheses and methods for total knee arthroplasty.

[0004] 2. The Relevant Technology

[0005] The knee is the largest and one of the most complicated joints ofthe human body. The human knee joint serves an essential function toallow individuals to lead a normal life, while performing its function,in many ways, much better than any device heretofore designed by humanengineers. For example, the knee should be able to move from 0° in thestraight position to more than 90°, while being completely stable inevery other direction.

[0006] The bones of the knee joint, when functioning properly, movetogether with very little friction. To function properly, a healthy kneejoint requires an intact layer of hyaline cartilage, the material thatmakes up the articular cartilage on opposing surfaces of the joint. Inaddition, the bones of the joint must be in proper alignment and thesynovial membranes must produce sufficient amounts of lubricating(synovial) fluid. Furthermore, the surrounding ligaments and tendonsmust prevent the bones from being placed in abnormal positions.

[0007]FIG. 1 is an anterior (that is, taken from the front of the body)cross-sectional view of a human knee 10. The knee 10 consists of threebones; a femur 20, a tibia 30, and a patella 40. Each of these bones iscovered with articular cartilage, which has a smooth glistening surface.Located at the distal end of femur 20 are the femoral condyles 22 havinga medial condyle 24 and a lateral condyle 26 separated by anintercondylar fossa or notch 28. Formation of intercondylar notch 28 issuch that patella 40 articulates therethrough during extension andflexion of knee 10.

[0008] Tibia 30 supports most of the weight transmitted between femur 20and the foot (not shown), while a small portion of the weight is carriedby a fibula 42 located substantially parallel to tibia 30. As such,tibia 30 has a tibial plateau 32 with a medial plateau 34 and a lateralplateau 36 substantially aligned to cooperate with medial condyle 24 andlateral condyle 26 of femur 20. Medial plateau 34 and lateral plateau 36of tibia 30 are separated by an intercondylar area formed with anelevated portion or an intercondylar eminence 38. Intercondylar eminence38 locates within intercondylar notch 28 to maintain structural supportbetween femur 20 and tibia 30. Additionally, intercondylar notch 28separates the spaces of a medial compartment 44 and a lateralcompartment 46 formed between the respective medial and lateral plateaus34, 36.

[0009] Located within each medial and lateral compartment 44 and 46 arethe menisci 50, shown by the dotted line. Menisci 50 consists of twocrescentic lamellae formed to distribute surface stresses between femur20 and tibia 30. As such, the upper surfaces of the menisci 50 aresmooth and concave to accommodate femoral condyles 24 and 26, while thelower surfaces are smooth and flat to cooperate with tibial plateaus 34and 36.

[0010] Surrounding and stabilizing the dynamic structure of knee 10 area number of varyingly sized ligaments. Particularly, four main ligamentsmaintain the stability and flexibility of knee 10: a medial collateralligament 62, a lateral collateral ligament 64, an anterior cruciateligament 66 and a posterior cruciate ligament 68. Medial collateralligament 62 and lateral collateral ligament 64 limit side-to-sidemotion. Medial collateral ligament 62 extends from medial condyle 24 orportions of femur 20 to medial plateau 34 of tibia 30. Similarly,lateral collateral ligament 64 extends from lateral plateau 36 orportions of femur 20 to fibula 42. Anterior cruciate ligament 66 andposterior cruciate ligament 68, so named because they cross in themiddle of knee 10, are rope-like ligaments formed from interwoven andoverlapping fibers. Anterior cruciate ligament 66 and posterior cruciateligament 68, extend from the anterior to the posterior of knee 10 andprevent femur 20 and tibia 30 from sliding forward and backward whilepermitting a wide range of rotational movement.

[0011] While the knee generally serves its purpose very well, variousdisorders of the knee cause a great deal of pain and loss of mobilityand function to those who are affected with such disorder. Some kneedisorders are congenital; that is, they are present at birth. Otherdisorders of the knee are brought on by bacterial infections that mayoccur at any age. Yet still other disorders result from normal “wear andtear” of the knee joint, whether such “wear and tear” arises from age orinjury. Perhaps the most wide spread disorder of the knee is arthritis.The term “arthritis” is generally used as a common name for the effectsof several degenerative knee disorders, such as by way of exampletraumatic arthritis, infectious arthritis, osteoarthritis, andrheumatoid arthritis.

[0012] Of various types of arthritis, osteoarthritis is perhaps the mostcommon. Osteoarthritis is a degenerative “wear and tear” process thataffects substantial numbers of people. The final result of uncheckedosteoarthritis is damaged articular cartilage, and subchondral bonewhich in many cases causes extreme pain as the damaged surfaces arerubbed together during joint movement. Osteoarthritis may also be causedby angular deformity or old fractures. Systemic arthritis such asrheumatoid arthritis or gout affects the synovium (the membrane tissuein the knee that normally lubricates the knee), becomes pathologic andone or more surfaces of the joint are destroyed.

[0013] Osteoarthritis may also involve the development of abnormal bonesubjacent to the joint surface, known as subchrondral lesions. Thesesubchrondral lesions may take the form of a cyst or sclerosis. Due tothe decreased stability of the knee through the generation of cysts andsclerosis and decreased joint space, marginal spurs develop in anattempt to stabilize the joint. Unfortunately, the spurs also causesevere pain, stiffness decreased range of motion, loss of stability, andloss of function.

[0014] Generally, osteoarthritis affects people past the age of 60 yearswithout providing any easily recognizable single cause. However,osteoarthritis may develop in younger people due to congenital disease.Furthermore, traumatic injury may cause development of an osteoarthritiscondition, such as from various sporting activities.

[0015] In the prior art, several methods have been used for alleviatingthe pain and improving the function of a knee joint affected with adegenerative disorder such as osteoarthritis. One of the most commonprocedures used in treatment of knee disorders is know as “arthroplasty”and entails the implantation of an artificial joint component into theknee. Arthroplasty has been one of the major areas of advancement inknee surgery during the past quarter century. Knee arthroplasty can takethe form of unicompartmental arthroplasty or total knee arthroplasty.

[0016] Unicompartmental arthroplasty involves replacement of one of thetwo compartments of the knee joint. For example, this procedure is usedwhere either of the medial or lateral compartments is damaged, while theremaining compartment and intercondylar notch are otherwise normal. Insuch a case, it is beneficial to replace the damaged areas of thefemoral condyle and tibial plateau with an artificial prosthesis thatwill work in conjunction with the natural portions of the knee.

[0017] The most common arthroplasty procedure used to alleviate pain andrestore knee function is total knee arthroplasty, also called total kneereplacement. While many different styles of total knee replacementprostheses have been implanted in patients, they generally resemble theprosthetic illustrated in FIG. 3.

[0018] Conventional total knee replacement involves a completeresurfacing of both tibial plateaus 34, 46 and femoral condyle 24, 26 assuggested in FIGS. 2 and 3. The conventional surgical procedure usedduring total knee replacement involves the insertion of one or all ofthe following artificial components into the knee; a one piece metallicfemoral component 70, a one piece metallic tibial tray component 74 witha polyethylene insert (not shown), and a one piece patellar component(not shown) of polyethylene. Each component 70 and 74 is adapted tocooperate one with another. As commonly used, femoral component 72 andtibial component 74 include one or more stems 78, as shown in FIG. 3,that are used to fixably attach respective components 72 and 74 to theirrespective bones.

[0019] As depicted in FIGS. 2 and 3, the present procedure for totalknee replacement is extremely invasive, causing significant damage tothe muscles, tendons and ligaments surrounding knee 10. The traditionalsurgical procedure entails making a large surgical incision over thefront of knee 10. Patella 40 is slipped across to the outside of knee 10to expose the joint between femur 20 and tibia 30, as shown by thedotted line. Any excess bone, such as subchrondral lesions, formed oneither femoral condyles 24 and 26, or tibial plateaus 34 and 36 isremoved and tight soft tissue carefully released so that knee 10 returnsto its normal shape without becoming too loose. Following removal ofexcess bone, the worn bone surfaces are cut away, while anteriorcruciate ligament 66 and posterior cruciate ligament 68 are removed. Theresultant bone surfaces are sized and holes 80 and 82 are drilled intofemoral condyle 22 and tibial plateau 24. Specifically, as shown in FIG.2, hole 80 is drilled into the medullary canal (not shown) toaccommodate tibial tray component 34.

[0020] During drilling of holes 80 and 82 high tolerances must bemaintained, since misalignment of femoral component 70 and tibial traycomponent 74 results in a misaligned knee joint, thereby eliminating thebeneficial effects of the surgical procedure. Once prepared, exactreplicas of the real artificial components are placed in position withholes 80 and 82 to allow testing of joint stability and dynamic motion.Upon completion of testing, the replicas are removed and the prostheticcomponents are fixed in position.

[0021] The most commonly accepted method of fixing femoral and tibialtray components 70 and 74 to femur 20 and tibia 30 is through the use ofa cement, such as polymethyl methacrylate (PMMA) or porous ingrowthpress fit. PMMA is a two-component acrylic cement that has the advantageof accepting a rapid setting time. After mixing the two components ofthe acrylic cement, holes 80 and 82 are “packed” with unset PMMA. Thestems of femoral component 70 are located within holes 82 while stem 78of tibial component 74 is located within hole 80. Both femoral component70 and tibial component 74 are maintained in place until PMMA sets. Oncethe PMMA has set, the insert (not shown) is located between tibial traycomponent 74 and femoral component 70 and the necessary positioning ofpatellar component 72 is performed.

[0022] Due to the various sizes and dimensions of knee 10, eachcomponent 70 and 74 is available in a wide variety of sizes and styles.During the surgical procedure, 10-20 different prosthetic components maybe available to a physician. Currently, most of the prosthetic femoralcomponents 70 and tibial tray components 74 are fabricated from alloyscontaining stainless steel, chromium, cobalt, molybdenum, or titanium.Such materials are inert within the body and maintain good mechanicalproperties. Tibial tray component 74 is most often made of titanium orstainless steel that is strong and leaves space for the insert. Theinsert traditionally comprises a plastic material, usually manufacturedfrom an ultra-high molecular weight polyethylene (UHMWP), because it ischemically similar to ordinary polyethylene but much harder and verysmooth. Unfortunately, there is a significant manufacturing cost withthese prostheses.

[0023] While the conventional total knee prosthesis procedure has beenpopularly accepted, major risks and drawbacks accompany its use. First,the required long incision either anteriorly or posteriorly disrupts theextensor mechanism of the knee, such as the quadricep muscles, thusprolonging rehabilitation.

[0024] Second, traditional total knee replacement requires the removalof a large amount of bone from femur 20 and tibia 30, whilenecessitating insertion of a large amount of foreign material. Insertionof foreign material creates a significant “dead space” in the knee wherean individual has no feeling, while increasing the risk of infection.

[0025] Third, the total knee replacement procedure eliminates thestability provided by both anterior and posterior cruciate ligaments 66and 68 of the knee 10. During current surgical procedures, commonly bothanterior and posterior cruciate ligaments 66 and 68 are removed.Therefore, only the combination of medial and lateral collateralligaments 62 and 64 with the configuration of the prosthesis maintains astability of knee 10.

[0026] Fourth, since tibial tray component 74 covers both the medial andlateral portions of tibial plateau 32, a tilting motion occurs duringnormal motion of knee 10. The tilting motion causes a predisposition toloosening of the bond between tibial tray component 74 and tibia 30.Furthermore, the abnormal motion of medial and lateral portions oftibial plateau 32 result in abnormal dynamic knee motion, therebydisrupting the normal “screw mechanism” of the knee, i.e. the externalrotation of tibia 30 relative to femur 20 in the final 20° motion of theknee extension. As such, an abnormal gait pattern can occur resulting ina predisposition for serious complications (such as loosening,infection, osteolysis, bone loss, etc).

[0027] Fifth, as mentioned earlier, the most common method of fixing thecomponents of a total knee prosthesis is by way of PMMA. PMMA cement isprepared by mixing two components together which harden into a solidmass by way of a chemical process. One of the two components is a finegranular powder of prepolymerized polymethyl methacrylate and the othercomponent is a liquid monomer. One constituent of the liquid monomer isN, N-Dimethyl-Para-Toluidine (DMPT), a toxic material. Other monomeringredients also exhibit adverse effects on humans. Thus, theintroduction of the mixed, but yet unset, PMMA, cement mixture intoholes 80 and 82, presents the potential of introducing a significantamount of toxic material into the blood stream, especially when locatingthe stems of the prosthesis into the medullary canal. Various reactionscan occur to PMMA cement, such as hypotension and even circulatorysystem collapse.

[0028] Aside from the immediate hazards that attend the use of PMMAcement, concern has also been expressed that there may be long termtoxicity, hypersensitivity, and carcinogenicity resulting from thematerials that make up prior total knee prosthesis, including cobalt,chrome, titanium, and polyethylene. In view of the uncertainty of theeffects of long-term use of these materials within the human body, ithas been considered advisable to reduce the contact between thesematerials and the body as much as possible.

[0029] Finally, in any surgical procedure there is the potential thatinfection may occur due to entry of microorganisms into the surgicalwound. Devastating infections are particularly difficult to prevent intotal knee replacement procedures due to the extensive invasion of thebody that is required. Special surgical techniques have been developedwhich reduce the risk of infection to the patient; unfortunately, thesesurgical techniques require far greater care than other types ofsurgical procedures, and in some cases are extremely cumbersome.

BRIEF SUMMARY OF THE INVENTION

[0030] It is a primary object of the invention to provide structures andmethods for reducing pain and instability, while improving function todamaged or diseased knees.

[0031] A particular object of the present invention is to providestructures and methods for augmenting portions of the femur and thetibia, in order to reduce or eliminate pain, improve range of motion,and enhance function of the joint.

[0032] Another object of the invention is to provide structures andmethods that minimize the quantity of bone mass required to be removedfor total or unicompartmental knee arthroplasty.

[0033] Another object of the invention is to provide structures andmethods for repairing a damaged or diseased knee joint which aresignificantly less invasive than prior art methods of knee arthroplasty.

[0034] Yet another object of the invention is to provide structures andmethods for reducing pain and increasing function of a diseased kneejoint in which foreign material presented to the body tissues and fluidsis reduced to a minimum.

[0035] Still yet another object of the invention is to providestructures and methods for repairing damaged or diseased portions of aknee that minimize the possibility and consequences of infectionentering the wound resulting from knee arthroplasty.

[0036] Another object of the invention is to provide knee prostheticstructures that are simpler to manufacture and cost less than thoseprostheses available at present.

[0037] Yet another object of the invention is to provide structures andmethods that reduce the wound size, surgical procedure time, and lengthof accompanying in hospital stay.

[0038] Still another object of the invention is to provide structuresand methods for reducing pain and increasing function of a knee thatresults in a less painful rehabilitation while achieving increased rangeof motion with similar stability as that of a healthy knee joint.

[0039] Still yet another object of the present invention is to preservethe anterior cruciate ligament and the posterior cruciate ligament topreserve a more normal gait pattern.

[0040] Yet another object of the present invention is to preserve thenormal radius of curvature of the knee, thus preserving the screw homemechanism of the knee.

[0041] Another object of the present invention is to provide for moreefficient boundary lubrication of the prosthetic components, thusreducing friction and associated problems.

[0042] To achieve the forgoing objects and in accordance with theinvention as embodied and broadly described herein, a knee jointprosthesis is disclosed. The knee joint prosthesis includes one or morefemoral components and one or more tibial components. The femoralcomponents are adapted for attachment to a femur of a patient whileretaining the cruciate ligaments. Each femoral component has a generallyspheroidal weight-bearing surface and includes a stem that is used tofixably attach the femoral component to the patient's femur. The tibialcomponent has a first surface configured to aid in attachment of thetibial component to a tibia while a second surface is adapted tocooperate with the bearing surfaces of the femoral components.

[0043] These and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more fully understand the manner in which theabove-recited and other advantages and objects of the present inventionare obtained, a more particular description of the invention will berendered by reference to specific embodiments thereof that areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are therefore notto be considered limiting of its scope, the invention will be describedand explained with additional specificity and detail through the use ofthe accompanying drawings in which:

[0045]FIG. 1 is a cross-sectional view showing the major structures ofthe human knee.

[0046]FIG. 2 is a partial cross-sectional view of a human knee in whichthe human knee has been prepared for total knee replacement, using aprior art prosthesis.

[0047]FIG. 3 is a partial cross-sectional view of a human knee in whicha total knee replacement common in the prior art has been implanted toreplace the natural knee.

[0048]FIG. 4 is a perspective view of the femoral and tibial componentsof a presently preferred embodiment of the present invention.

[0049]FIG. 5 is a cross-sectional view of a femoral component of theembodiment illustrated in FIG. 4 taken along line 5-5 of FIG. 4.

[0050] FIGS. 6A-6G are perspective views of alternate configurations offemoral components in accordance with the present invention.

[0051] FIGS. 7A-7C are perspective views of alternate configurations ofthe tibial components in accordance with the present invention.

[0052]FIG. 8A is a partial cut-away perspective view of the knee jointbefore removal of portions of the femoral condyle and tibial plateaubefore implantation of the knee joint prosthesis of the presentinvention.

[0053]FIG. 8B is a partial cut-away perspective view of the knee jointafter removal of portions of the femoral condyle and tibial plateaubefore implantation of the knee joint prosthesis of the presentinvention.

[0054]FIG. 8C is a partial cut-away perspective view of the knee jointafter implantation of four femoral components and a tibial component ofthe knee joint prosthesis of the present invention.

[0055]FIGS. 8D is a partial cut-away perspective view of the knee jointwith the total knee joint prosthesis of the present invention implanted.

[0056]FIG. 9 is a partial cut-away perspective view of a knee joint thatincludes a alternate form of a total knee joint prosthesis in accordancewith the present invention.

[0057]FIG. 10 is a partial cut-away perspective view of a knee jointthat includes an alternate form of a tibial prosthetic component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] (a) Introduction

[0059] The present invention includes various prosthetic components andmethods for surgically implanting such prosthetic components in a humanknee to reduce pain, improve motion, and enhance function of a diseasedor damaged knee joint. Each prosthetic component is sized and shaped toallow the method for implantation to minimize the wound size andinvasiveness of the surgical procedure, thereby reducing cost, hospitalstay, rehabilitation time, and pain.

[0060] Generally, a patient postpones obtaining medical treatment untilthe pain due to a knee disorder is severe. By this time, various partsof the knee are generally involved in causing the patient's pain and acorresponding reduction of knee motion and function, such as the femoralcondyle, the tibial plateau, the patella, and the menisci. It isfrequently necessary to take corrective action by treating all of theabove knee elements. The present invention includes both femoral andtibial prosthetic components adapted for replacement of damaged tissueand bone, whether for total or unicompartmental knee joint replacement.Generally, the components will be used in cooperation with each other,although it should be understood that single components might beutilized to obtain the desired result.

[0061] The following description is divided into several parts in orderto improve clarity of the description and to assist the reader inunderstanding the concepts involved. First a description of variouscauses of pain in the knee are given so that is will be clear how thepresent invention helps to reduce or eliminate such pain and thusimprove knee joint motion and function. Upon this foundation, a detaileddescription of the presently preferred embodiments of the presentinvention is provided together with a brief explanation of protocols andprocedures in accordance with the invention.

[0062] (b) Localization of Knee Pain

[0063] As described previously, there are various reasons for painwithin knee joints. Such pain can result from sporting injuries oraccidents, hereditary joint malformation or disease, contracteddiseases, or simply “wear and tear.” Each particular infirmity canaffect the knee joint in a different manner. For example, malformationof joint surfaces can cause joint instability, deterioration of internalbone structures resulting in the disintegration of bone mass, orelimination of the menisci.

[0064] Generally, pain occurs when the bony surfaces of the femur andtibia come into contact. Specifically, pain can result when the bonymedial and lateral condyles of the femur grind against the medial andlateral surfaces of the tibial plateau, whether as a result ofdeterioration of the articular cartilage between the surfaces of thefemur and the tibia, or due to some other reason which will beappreciated by one skilled in the art. Due to the structure of theskeleton, constant force is applied to the femoral and tibial surfacesduring normal physical activity, such as walking. In the case where themenisci has disintegrated or thinned, the medial and lateral collateralligaments and the anterior and posterior cruciate ligaments maintainfemoral and tibial surfaces in contact, even when seated, therebygenerating pain. Pain can also result from the creation of subchrondrallesions that scrape against either the femoral condyles or tibialplateaus. Although there is considerable debate within the medicalprofession as to the exact cause of knee pain, it is clear that byseparating bone surfaces the pain is substantially reduced oreliminated.

[0065] (c) Description of the Components of the Presently PreferredEmbodiments of the Present Invention

[0066] As previously stated, the preferred method for preventing pain tothe patient is to remove diseased portions of the femoral and tibialarticulating surfaces and implant femoral and tibial components. Thisprocedure causes a separation between the bone surfaces, therebyeliminating knee pain. The present invention effectively creates bonesurface separation in a substantially less invasive manner.

[0067] Reference will now be made to FIGS. 4-10 to describe thestructure of the components of the presently preferred embodiments. Inthe drawings, like structures are marked with like numerals.

[0068] One presently preferred embodiment of the present invention isshown in perspective in FIG. 4. The structure of this embodimentincludes two prosthetic components useful in either total orunicompartmental knee replacement of portion of the intercondylar notchand/or and the medial and lateral condylar surfaces of femoral condyles22 and the tibial plateaus of tibial plateau 32. The structure of FIG. 4includes at least one femoral component 90 and at least one tibialcomponent 100. It can be appreciated that in some situations a patellarcomponent and/or an insert may also form part of the structure, so longas such components are adapted for use with the methods and apparatus ofthe present invention. As mentioned previously, the present inventionmay use both prosthetic components 90 and 100 together or separately toachieve the beneficial effect of total or unicompartmental kneereplacement.

[0069] As depicted, femoral component 90 has a generally T-shapedcross-section, as better seen in FIG. 5, and includes a lower surfaceportion 92 having a substantially spheroidal shape, and a generallyplanar superior surface 94 with a fixation post or stem 96 extendingtherefrom. The term “spheroidal,” as used herein, refers to a surfacewhich may either be perfectly spherical, or which departs therefrom,such as being elliptical, or the like. Additionally, spheroidal refersto elongated surfaces having a curved, spherical, or the like profiles.Generally, lower surface portion 92 can take various forms so long as itis capable of cooperating with respective surfaces of tibial components100. Additionally, lower surface portion 92 acts as a bearing surfacethrough which the weight of the patient is transferred to tibialcomponent 100. Lower surface portion 92 is preferably polished to amirror-type finish to thereby reduce friction between femoral condyle 22and tibial plateau 32 and enhances smooth movement of knee 10.Additionally, lower surface portion 92 may be hardened throughconventional processing steps to protect the finished surface during useof femoral component 90. As such, lower surface portion 92 is preferablyconfigured from the same material as the rest of femoral component 90,such as but not limited to polyethylene, ceramic, stainless steel,titanium, and the like, or alternatively may be configured from aninsert manufactured from a different material than that of the rest offemoral component 90. Furthermore, though it is preferred that lowersurface portion 92 be fabricated from substantially the same materialsas the rest of femoral component 90, it is contemplated that a frictionreducing coating or finish may be applied to lower surface portion 92,such as diamond, and the like, to aid in the movement of the knee joint.

[0070] Superior surface 94 is depicted as having a generally planarform, although, various other configurations are also possible, such ascurved, spheroidal, angular, or the like, dependent on the particularportion of femoral condyle 22 that is affixed to femur 20. Additionally,superior surface 94 need not be circular in cross-section but may havevarious other shapes such as, by way of example only, square,triangular, octagonal, hexagonal, oval, trapezoidal, rectangular, or thelike.

[0071] As referenced previously, femoral component 90 is provided with astem 96. Stem 96 is depicted as having a generally cylindrical form,although other configurations, shapes and, lengths are possible. AsFIGS. 4 and 5 depict, the surface of stem 96 as being generally smooth,although this is not necessary. Stem 96 is adapted to fixably attach tofemur 20 and retain femoral component 90 thereto. Stem 96 can,therefore, have various dimensions, sizes, shapes, and cross-sections solong as it is capable of fixably attaching femoral component 90 to femur20. By way of example and not limitation, such steps include, but arenot limited to round, square, oval, triangular, or the like.

[0072] Femoral component 90 can have various other configurations,shapes, and dimensions, such as these shown in FIGS. 6A-6G, which shallbe described hereinafter. The various configurations can be chosen inlight of the size of knee 10, the amount of damage to knee 10, thecooperation between tibial component 100 and femoral component 90, orother reasons that will be appreciated by one skilled in the art.

[0073] Femoral component 90 may be advantageously fabricated fromvarious materials, such as metals, ceramics, plastics, or combinationsthereof with or without porous ingrowth coatings. In one preferredembodiment, femoral component 90 is fabricated from a stainless steelalloy known in the art as 316L. Stainless steel 316L has the advantageof being easily machined, an economical method of fabrication whendealing in small quantities.

[0074] Tibial component 100, as depicted in FIG. 4, has a generallyrectangular form having an upper surface 102 and a lower surface 104.The configuration of upper surface 102 is such to cooperate with femoralcomponent 90. As shown, upper surface 102 is generally planar and ispreferably polished to a mirror-type finish similar to lower surfaceportion 92 of femoral component 90. Upper surface 102, may be concave toallow mating with femoral component 90, such as shown in FIGS. 7A and7B, or may be angularly oriented, or have some other form, such as shownin FIG. 7C. Lower surface 104, as shown in FIG. 4, is also preferablyplanar and is shaped to cooperate with medial and lateral plateaus 34and 36 of tibial plateau 32. Although depicted as having a rectangularshape in FIG. 4, lower surface 104 can be concave, convex, planar,angular, or the like, dependent on whether lower surface 104 is insertedwithin tibial plateau 32, on the surface of medial plateau 34 or lateralplateaus 34, or in some other manner.

[0075] Generally, a single tibial component 100 is located within achannel 130 either adjacent to, near, or within each of medial plateau34 and/or lateral plateau 36 of the proximal tibia 32 (as shown in FIGS.8B, 8C, and 8D). It should be appreciated, however, that two or moretibial components 100 can be used, such as shown in FIGS. 9 and 10. Inanother configuration, only one tibial component 100 is required ineither medial plateau 34 or lateral plateau 36.

[0076] Tibial component 100 can have various other configurations,shapes, and dimensions, such as those shown in FIGS. 7A-7C, which shallbe described hereinafter. The various configurations can be chosen inlight of the size of knee 10, the amount of damage to knee 10, thecooperation between tibial component 100 and femoral component 90, orother reasons that will be appreciated by one skilled in the art, suchas but not limited to ligament tensioning.

[0077] Additionally, tibial component 100 may be fabricated from variousmaterials such as metals, ceramics, plastics, or combinations thereofwith or without porous ingrowth coatings. It is preferred that tibialcomponent 100 be substantially composed of a metallic material.

[0078]FIG. 6A depicts, an alternate configuration of femoral component190. The majority of the features previously discussed with respect tofemoral component 90 also apply to femoral component 190. Femoralcomponent 190 includes a transition portion 197 that extends fromsuperior surface 194. Transition portion 197 includes sides that aresubstantially perpendicular to superior surface 194. The transitionportion 197 of femoral component 190, in this configuration, can becountersunk into hole 82 formed in femur 20. By so doing, increasedstrength is give to the bond between femoral component 190 and femur 20due to the increase in area in contact with the bone. It can beappreciated that the sides of femoral component 190 need not besubstantially perpendicular to superior surface 194, but can beangularly oriented relative to superior surface 194.

[0079]FIG. 6B depicts another alternate configuration of femoralcomponent 190 b. The majority of the features previously discussed withrespect to femoral component 190 also apply to femoral component 190 b.Femoral component 190 b includes a multi-transition portion 197 b thathas a “step” configuration, such that the configuration of femoralcomponent 190 b allows countersinking of transition portion 197 b offemoral component 190 b in femur 20. Through the “step” configuration,femoral component 190 b bonds more securely to femur 20. It can beappreciated that transition portion 197 b may be repeated a number oftimes to increase the bonding. Additionally, femoral component 190 bincludes a coating 208 applied to lower surface 192 b that reducesfriction and allows smoother movement between the femoral and tibialcomponents. Coating 208 may include a diamond coating, or any othercoating that may reduce friction between the femoral and tibialcomponents. Though it is preferred that femoral component 190 b does notinclude coating 208, due to the difficult in preventing dislodging ofcoating 208 during use, it is contemplated that the present inventionmay use coating 208 if and when required.

[0080]FIG. 6C depicts another alternate configuration of a femoralcomponent 190 c. The majority of the features previously disclosed withrespect to femoral component 90 also apply to femoral component 190 c.Stem 196 c of femoral component 190 c includes a plurality of raisedportions 198 c that project from the surface thereof. The particularconfiguration of the plurality of raised portions 198 c may vary toassist in securely retaining femoral component 190 c on femoral condyle22. Therefore, the size, shape and configuration of the plurality ofraised portions 198 c may vary, so long as they cooperate with the size,shape and configuration of stem 196 c to fixably attach femoralcomponent 190 c to femur 20. Therefore, raised portions 198 c can takethe form of angled wedges, threads, spikes, channels, or some other formto aid in locking stem 196 c within femur 20.

[0081] The plurality of raised portions 198 c on stem 196 c is onestructure capable of performing the function of attachment means forassisting in the attachment of femoral component 90 to femur 20. Othersuitable structures are appropriate, and are known by one skilled in theart.

[0082]FIG. 6D depicts, another alternate configuration of a femoralcomponent 190 d. The majority of the features previously discussed withrespect to femoral component 90 also apply to femoral component 190 d.Femoral component 190 d includes a spheroidal lower surface portion 192d that has a large cross-sectional area. The large surface area of lowersurface portion 192 d allows fewer femoral components 190 d to be usedduring total or subtotal knee replacement; therefore, resulting in fewerholes 82 being formed in femur 20. By so doing, total or subtotal kneereplacement is quicker and less invasive. Additionally, extending fromand formed with lower surface portion 192 d is a transition portion 197d that has the same cross-sectional dimension as the largestcross-sectional dimension of lower surface portion 192 d. As previouslydiscussed, transition portion 192 d allows for a more secure attachmentof femoral component 190 d to femur 20 due to the increase surface areathat comes into contact with femur 20.

[0083]FIG. 6E depicts, another alternate configuration of a femoralcomponent 190 e. The majority of the features previously discussed withrespect to femoral component 90 also apply to femoral component 190 e.Femoral component 190 e includes a transition portion 197 e that extendsfrom superior surface 194 e. Transition portion 197 e includes sidesthat are substantially perpendicular to superior surface 194 e.Transition portion 197 e of femoral component 190 e, in thisconfiguration, can be countersunk into hole 82 formed in femur 20. By sodoing, increased strength is give to the bond between femoral component190 e and femur 20 due to the increase in area in contact with the bone.It can be appreciated that the sides need not be substantiallyperpendicular to superior surface 194 e, but can be angularly orientedrelative to superior surface 194 e.

[0084]FIG. 6F depicts, another alternate configuration of a femoralcomponent 190 f. The majority of the features previously discussed withrespect to femoral component 90 also apply to femoral component 190 f.Femoral component 190 f includes a spheroidal lower portion 192 f thathas a generally rectangular configuration. Lower portion 192 f has alarge cross-sectional area similar to that of lower portion 192 e. Therectangular configuration allows a secure cooperation between lowerportion 192 f and a rectangular upper surface 102 of tibial component100. The configuration of femoral component 190 f further allows asurgeon to implant fewer femoral components 190 f due to the largersurface area covered by each femoral component 190 f.

[0085]FIG. 6G depicts, another alternate configuration of a femoralcomponent 190 g. The majority of the features previously disclosed withrespect to femoral component 90 also apply to femoral component 190 g.Femoral component 190 g has a similar form to that of femoral component190 f, however, stem 196 g of femoral component 190 g includes aplurality of raised portions 198 g that project from the surfacethereof. The particular configuration of plurality of raised portions198 g may vary to assist in securely retaining femoral component 190 gon femoral condyle 22, as was described with reference to raisedportions 198 c.

[0086] The plurality of raised portions 198 g on stem 196 g is anotherstructure capable of performing the function of attachment means forassisting in the attachment of femoral component 90 to femur 20. Othersuitable structures are appropriate, and known by one skilled in theart.

[0087] Modification of the various configurations, dimensions, shapes,sizes and characteristics of femoral components 90, 190 and 190 b-190 gis possible, and include, but are not limited to, head diameters, stemdiameters, inclusion or exclusion of threads, barbs or the like that actas attachment means, first and second transition portion diameters,depth parameters, surface finishes, and the like. Additionally, theconfiguration of femoral components 90, 190, and 190 b-190 g is suchthat it is possible to implant one or more femoral components 90, 190,and 190 b-190 g without the need to cut or sever any of the cruciateligaments. As used herein the word “sever” will mean cutting, cleaving,detaching, separating, disconnecting, or otherwise stopping coupling offemur 20 and tibia 30 through the cruciate ligaments. It will beappreciated that the configurations of femoral components discussedherein are only illustrative and should not be considered as limitingthe applicability of other femoral component configurations.

[0088]FIG. 7A depicts another alternative configuration of a tibialcomponent 100 a. The majority of features previously discussed withrespect to the component 100, also apply to tibial component 100 a. Asshown, tibial component 100 a includes a generally curved upper surface102 a. The particular configuration of upper surface 102 a is such thatincreased matting is generated between femoral components 90, 190 and190 b-190 g, and tibial components. As discussed previously, it can beappreciated that upper surface 102 a may take various forms.

[0089]FIG. 7B depicts another alternate configuration of a tibialcomponent 100 b. The majority of the features previously disclosed withrespect to tibial component 100 also apply to tibial component 100 b. Asshown, tibial component 100 b includes at least one stem 106 extendingfrom lower surface 104 b that are capable of being fixably attachedwithin one or more holes (not shown) formed in tibial plateau 32. Stems106 can have various forms such as those described with reference tostems 96 and 196 a-196 g.

[0090] Tibial component 100 b optionally includes a coating 108 formedon upper surface 102. Coating 108 is generally formed to aid in thereduction of frictional forces between femoral condyle 22 and tibialplateau 32. Such coating 108 may have a similar configuration as that ofcoating 208. Though it is preferred that upper surface 102 b be polishedor otherwise finished to reduce frictional forces, it is possible to usea coating 108 to perform the same function.

[0091]FIG. 7C depicts another alternate configuration of a tibialcomponent 100 c. The majority of the features previously disclosed withrespect to tibial component 100 also apply to tibial component 100 c.Tibial component 100 c has a generally trapezoidal cross-section havingan upper surface 102 c and a lower surface 104 c. The surface area ofupper surface 102 c is substantially smaller than lower surface 104 cand has a smaller width. As such, when tibial component 100 c is fixedwithin channel 130 that has a similar generally trapezoidalcross-section, as shown in FIG. 10, the combination of the configurationof tibial component 100 c and channel 130 prevents movement of tibialcomponent 100 c generally parallel to the longitudinal axis of tibia 30.Through this configuration, tibial component 100 c is more securelyfixed within tibial plateau 32. It can be appreciated by one skilled inart that various other configurations of tibial component 100 c arecapable of performing a similar function.

[0092] Generally, tibial components 100, 100 b, and 100 c lmay havevarious sizes, dimensions, and shapes so long as tibial components 100,100 b, and 100 c are capable of being implanted within tibia 30 withoutsevering a cruciate ligament.

[0093] (d) Description of the Procedures and Protocols of the PresentlyPreferred Embodiments of the Present Invention

[0094] The present invention will have application in reducing pain dueto several knee disorders, and is particularly applicable for use incases involving osteoarthritis, rheumatoid arthritis, and traumaticarthritis of the knee.

[0095] A candidate for implementation of the present invention ispreferably chosen by considering several factors. Generally, a patientseeking the advice of an orthopedic surgeon complains of knee pain andstiffness, swelling of the joint accompanying diminished function. Anexamination of such a patient may reveal a limp, some discrepancy in theindividual's limb length, or even severe misalignment of the limb. Aradiological examination will often verify diagnosis of osteoarthritis,rheumatoid arthritis, and traumatic arthritis of the knee. Dependingupon the classification of the condition and the particular suitabilityof the patient for the procedure, the patient will either be accepted orrejected as a candidate for the present invention.

[0096] During the procedure of the present invention, large portions ofthe patient's femoral and tibial condylar surfaces are saved. Theconfiguration, size, shape, number, and position of the prostheticcomponents, of the present invention must be selected to properlycomplement the shape of the patient's medial and/or lateral plateausurfaces. Thus, it is helpful to utilize radiological and otherexamination techniques to carefully determine the size, shape, number,and position of femoral component 90 and tibial component 100 that wouldbe best suited for a particular patient. It is anticipated thatavailability of a series of various sized and shaped prostheticcomponents will allow the surgeon to select a set that will provide anappropriate fit for a particular patient.

[0097] The presently preferred method of the present invention involvespreparing the patient pre-operatively in a conventional fashion similarto that generally used for major knee surgery. Once the patient is takento the operating room, the patient is preferably placed in a supineposition and draping and preparation of the knee joint is completed.Anesthesia is also initiated.

[0098] While many surgical approaches to total knee replacement requirea large incision, traversing from the lower portion of femur 20 or thighover the patella of knee 10 and to the upper portion of the anteriortibia or leg, the present invention can be practiced using only smallincisions or portals 110 and 112 (see FIG. 8A) on one or both sides ofthe patellar tendon (not shown), thereby minimizing the wound size andinvasiveness of the surgical procedure. Furthermore, while presentsurgical procedures disrupt the quadricep mechanism: rectus femoris,vastus lateralis, vastus medialis, and vastus intermedius and theposition of the patella or patellar ligaments, thereby increasingrehabilitation time, the use of small incisions 110 and 112 do notaffect the quadricep mechanism or the position of the patella, againminimizing the wound size and invasiveness of the surgical procedure.

[0099] Small incisions 110 and 112 pass through the epidermis and dermisand are deepened through subcutaneous tissues and then the jointcapsule, while hemostais is obtained by electrocautery. Each incision110, 112 is so positioned as to allow access to femoral condyles 24, 26,and tibial plateaus 34 and 36, respectively, by way of open surgicalprocedures or through the use of arthroscopic procedures, as describedin this illustrative embodiment of the method of the present invention.As such various types of equipment 120, both for arthroscopic and opensurgical procedures, may be used and included, by way of example only,an arthroscope 122 and other types of surgical instruments 124,including saws, chisels, retractors, or suction apparatus.

[0100] The surgeon raises the patient's leg and bends knee 10 to allowexamination of femoral condyles 22 and tibial plateaus 32 or “jointsurfaces” to determine the best location for the components of thepresent invention. Specifically, the surgeon identifies the location ofgreatest wear on both femoral condyle 22 and tibial plateau 32.Additionally, the axis of knee 10 and rotational motion of knee 10 areanalyzed to identify the desired implantation location. As part of kneeaxis and motion analysis, defects such as subchrondral lesions, areaddressed before sizing of knee components to knee 10.

[0101] Utilizing FIGS. 8A-8D, reference will now be made to implantationof the various components of the present invention by way of anarthroscopic surgical procedure; however, it can be appreciated by oneskilled in the art that implantation of the various components of thepresent invention may be performed through an open surgical procedurewhere no arthroscopic equipment us utilized. Discussion will further bemade to implantation of components on medial condyles 24 and 34 of femur20 and tibia 30, respectively. It can be appreciated, however, that asimilar procedure may be performed through incision 112 with respect tolateral condyles 26 and 36 of femur 20 and tibia 30, if required.

[0102] A channel, generally indicated by reference numeral 130 in FIG.8B, is formed in tibial plateau 32 and traverses medial plateau 34 oftibia 30. Channel 130 is formed to cooperate with femoral component 90that is attached to medial plateau 34 of femur 20, thereby creating aseparation of femur 20 and tibia 30. Channel 130 requires a portion oftibial surface 32 to be removed, preferably by using a reciprocating sawand chisel that pass through incision 110, that is maintained in theopen position by way of retractors 126, as shown in FIG. 8A. Othermethods are known by one skilled in the art to form channel 130 by wayof open, “key-hole”, and arthroscopic surgical techniques. As such, asaw is inserted through incision 110, while arthroscope 122 is insertedthrough incision 112 to allow light and observation of the surgicalsite. Alternatively, light and observation of the surgical site may beachievable by looking through incision 110, in the event that an opensurgical procedure is performed. Whether through arthroscopic or opensurgical procedures, portions of the proximal tibia 32 are removed untilthe required dimensions are achieved.

[0103] As shown, channel 130 has a generally rectangular cross-section,although other configurations are possible so long as channel 130cooperates with tibial component 100.

[0104] Upon formation of channel 130, the position of knee 10 ismanipulated as needed so as to allow access to femoral condyle 22 andassociated surfaces of medial condyle 24. Once knee 10 is positioned, soas to render the desired portion of femoral condyle 22 visible to thesurgeon, the surgeon verifies the axis of knee 10 and range of motion ofknee 10 with respect to channel 130. After defining the axis of knee 10and range of motion of knee 10 the surgeon defines the axis of medialcondyle 24 of femur 20 and forms an anchoring hole 132, such as by wayof a conventional arthroscopic surgical drill 125, as shown in FIG. 8Beither alone or in combination with other surgical apparatus such as butnot limited to one or more guide wires, jigs, and the like.

[0105] Anchoring hole 132 is sized and configured to cooperate withfemoral component 90. However, anchoring hole 132 may be varied toaccommodate femoral component 90 in its various forms, such as but notlimited to those described herein. For example, anchoring hole 132 iscountersunk to allow the required seating of superior surface 92 andtransition portion 97 against various surfaces of medial condyle 24.

[0106] After channel 130 and anchoring hole 132 have been formed, thesurfaces of femoral condyle 22 and tibial plateau 32 are thoroughlycleansed with a pulsating water lavage and antibiotic irrigation, whilesimultaneously, all waste products are removed from the surgical sitevia arthroscopic suction apparatus, as known by one skilled in the art.The selected femoral component 90 is inserted and secured withinanchoring hole 132 by the use of PMMA, as shown in FIG. 8C. As can beappreciated, other methods, such as using porous bone ingrowthtechniques, cements, or the like may be used to fix femoral component 90in place. The combination of PMMA or other similar bonding techniqueswith raised portions 98 and stem 96 is another example of one structurecapable of performing the function of attachment means for assisting inthe attachment of femoral component 90 to femur 20.

[0107] Once femoral component 90 is inserted, the excess PMMA is removedfrom the surface of femoral condyle 22 such that no PMMA extends pastfemoral component 90. Femoral component 90 is inserted to a depth suchthat lower surface portion 92 of femoral component 90 protrudes fromabout 2 mm to about 15 mm above the femoral condyle surface 22. In analternative configuration, femoral component 90 protrudes from about 4mm to about 10 mm above the femoral condyle surface 22. In a preferredconfiguration, femoral component 90 protrudes about 5 mm to about 8 mmabove the surface of femoral condyle surface 22.

[0108] Once femoral component 90 is in place, the surgeon manipulatesknee 10 until the location for fixation of additional femoral components90 is in sight through incision 110. Upon sighting of the next insertionsite, the surgeon then follows the above procedure to implant anotherfemoral component 90.

[0109] This process is repeated as necessary over as much of the surfaceof femoral condyle 22 as is necessary, including the intercondylar notch28. Femoral condyle 22, therefore, may be covered with a plurality offemoral components 90, such as shown in FIGS. 8C, 8D, 9 and 10.

[0110] Upon completion of implantation of the desired number of femoralcomponents 90, the surgeon next turns to the implantation of tibialcomponent 100. Tibial component 100 is located within channel 130 andsized to effect a separation between femoral condyle 22 and tibialsurface 32. Additionally, the configuration of tibial component 100 issuch that the cooperation between femoral component 90 and tibialcomponent 100 results in a stable joint. Furthermore, the size anddimensions of tibial component 100 aid in the correction ofmalformations of femoral condyle 22 and/or tibial plateau 32 caused bythe presence of subchrondral lesions. By so doing medial collateralligaments 62, lateral collateral ligaments 64, anterior cruciateligaments 66, and posterior cruciate ligaments are preserved, tightened,and maintain stability to knee 10.

[0111] Tibial component 100, as shown in FIG. 8C, is inserted intochannel 130 and fixably attached by way of PMMA or some other methodknown by one skilled in the art or described herein. As describedherein, tibial component 100 may have various configurations anddimensions to accommodate various knee problems. For example, multipletibial components 100 can be used within each medial and lateral plateau34 and 36 of tibia 30, as shown in FIGS. 9 and 10.

[0112] Once all requisite prosthetic components are in place to thesatisfaction of the surgeon, as shown in FIGS. 8C, 8D, 9 or 10,antibiotic irrigation is once again performed so as to reduce thepossibility of infection, and equipment 120, whether arthroscopicprocedure or open surgical procedure equipment is removed. Finally, therequisite surgical closing procedures are performed, such as insertionof a drain brought down anteriorly from the depths of the wound, andclosure and dressing of the surgical wound. Once the surgical procedureis completed, the patient is taken to recover post-operatively, andX-rays may be obtained to check the results of the procedure.

[0113] As described herein, the insertion and fixation of tibialcomponent 100 was described as occurring after the insertion andfixation of one or more femoral components 90. As will be appreciated byone skilled in the art, insertion and fixation of tibial component 100may occur before insertion and fixation of femoral component 90.Additionally, insertion and fixation of tibial component 100 may occurbefore drilling of anchoring hole 132.

[0114] Generally speaking, the beneficial effects of the surgicalprocedure of the present invention assists in the substantialelimination of pain resulting from deterioration of the knee joint, in asubstantially less evasive manner than presently taught, while providingstrong and durable prosthesis. As such, the use of minor incisions,arthroscopic equipment, and lack of disruption to the surroundingmuscles, tendons and ligaments results in a reduction in the risk ofinfection, an increase in the mobility and stability of the knee jointafter surgery, and an accelerated hospital stay with less rehabilitationtime.

[0115] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A prosthetic knee component adapted for attachment to asurface of a patient's knee through a portal associated with a minimallyinvasive surgical procedure, the prosthetic knee component comprising: afirst portion adapted for fixable attachment to the surface of the knee;and an elongated, generally spheriodal second portion disposed oppositeto said first portion, said second portion being adapted to extend overa portion of the surface of the knee between an anterior portion and aposterior portion of the knee.
 2. The prosthesis as recited in claim 1,wherein said second portion extends between the anterior portion and theposterior portion of a femur.
 3. The prosthesis as recited in claim 1,wherein said second portion is adapted to reduce friction.
 4. Theprosthesis as recited in claim 1, wherein said first portion includesattachment means for assisting the attachment of the prostheticcomponent to the surface of the knee.
 5. The prosthesis as recited inclaim 4, wherein said attachment means comprises a plurality of raisedportions extending from said first portion.
 6. The prosthesis as recitedin claim 1, wherein said second portion has a generally ovalconfiguration.
 7. The prosthesis as recited in claim 1, wherein theprosthetic knee component further includes a transition portionintermediate of said first portion and said second portion.
 8. Theprosthesis as recited in claim 1, wherein said first portion is adaptedwith at least one thread that substantially encompasses said firstportion.
 9. A knee joint prosthesis for attachment to a femur and atibia of a patient during unicompartmental or total knee replacement,the prosthesis comprising: a plurality of femoral components configuredto be attached to the femur, each of said plurality of femoralcomponents having a first portion adapted for fixable attachment to thefemur and an elongated second portion formed with a spheroidal bearingsurface and adapted to extend over a portion of the femur between ananterior portion and a posterior portion of the femur, said femoralcomponent being configured so as to permit attachment to the femurthrough one or more portals associated with a minimally invasivesurgical procedure and without severing both of the cruciate ligaments;and at least one tibial component having a first surface adapted tocooperate with the tibia and a second surface adapted to cooperate withat least two of said plurality of femoral components affixed to thefemur disposed opposite the at least one tibial component affixed to thetibia, said tibial component being configured so as to permit attachmentto said tibia through one or more portals associated with a minimallyinvasive surgical procedure and without severing both of the cruciateligaments.
 10. A prosthesis as recited in claim 9, wherein said firstportion of said femoral component includes a stem for insertion intosaid femur.
 11. A prosthesis as recited in claim 9, wherein said tibialcomponent has a generally rectangular form, wherein said first surfaceand said second surface are substantially planar.
 12. A prosthesis asrecited in claim 9, wherein said tibial component is formed from twotibial component portions.
 13. A prosthesis as recited in claim 9,wherein said bearing surface is covered with a friction reducingcoating.
 14. A prosthesis as recited in claim 9, wherein said femoralcomponent further comprises a transition portion intermediate of saidfirst portion and said second portion.
 15. A prosthesis as recited inclaim 9, wherein said second portion has an oval configuration.
 16. Atotal knee joint prosthesis, comprising: a femoral component adapted forattachment to a femur of a patient while substantially maintaining theexisting shape of one or more condyles of the femur, said femoralcomponent comprising an elongated, spheroidal portion and a stemextending from said elongated, spheroidal portion; and a tibialcomponent having a first surface configured to aid in attachment of saidtibial component to a tibia and a second surface adapted to cooperatewith said elongated, spheroidal portion of said femoral component.
 17. Aprosthesis as recited in claim 16 wherein said stem is formed withattachment means for assisting the attachment of said femoral componentto said femur.
 18. A prosthesis as recited in claim 17, wherein saidattachment means includes a plurality of raised portions.
 19. Aprosthesis as recited in claim 16, wherein said first surface includes astem extending therefrom.
 20. A prosthesis as recited in claim 16,wherein said tibial component has a generally trapezoidal configurationwith said second surface having a curved profile to cooperate with saidelongated, spheriodal portion.
 21. A prosthesis as recited in claim 16,wherein said second surface is angularly orientated relative to saidfirst surface.
 22. A method of repairing a patient's damaged knee, whilepreserving at least one cruciate ligament, comprising the steps of:obtaining a prosthetic component adapted for fixable attachment to asurface of the patient's knee and being capable of separating e femoralcondyle and a tibial plateau, the prosthetic component comprising: afirst portion adapted for fixable attachment to the femoral condyle ofthe knee; and an elongated, generally spheriodal second portion disposedopposite said first portion, said second portion being adapted to covera portion of the surface of the knee between an anterior portion and aposterior portion of the surface of the knee; preparing the patient'sknee for implantation of said prosthetic component by way of at leasttwo minimally invasive portals formed in tissues surrounding the femoralcondyle and the tibial plateau, the at least two small portals soconfigured to result in minor wounds following repairing the patient'sdamaged knee; and implanting said prosthetic component into the surfaceof the knee by way of said at least two portals thereby separatingportions of the femoral condyle and the tibial plateau.
 23. The methodas recited in claim 22, wherein said knee joint prosthesis furthercomprises a tibial component having an upper surface adapted tocooperate with said second portion.
 24. The method as recited in claim23, wherein said tibial component comprises a first surface adapted tocooperate with the tibial plateau and a second surface adapted tocooperate with said second portion.
 25. The method as recited in claim22, wherein the step of preparing the patient's knee comprises: creatingat least two portals in the knee to allow access to the knee joint; andpositioning at least one surgical apparatus through at least one of saidat least two portals.
 26. The method as recited in claim 22, wherein thestep of implantation comprises: identifying the motion of the kneejoint; verifying the implantation location of the knee joint prosthesisbased on the motion of the knee joint; forming one or more anchoringholes to accommodate the knee joint prosthesis; and fixing the kneejoint prosthesis within the knee joint by way of the anchoring hole. 27.The method as recited in claim 26, wherein the step of forming one ormore anchoring holes comprises drilling one or more anchoring holes inthe femoral condyle.
 28. The method as recited in claim 27, furtherincluding the step of forming a channel in a tibial plateau, the channelbeing adapted to receive a tibial component.
 29. The method as recitedin claim 28, wherein the fixing step comprises positioning the firstportion within one of said one or more anchoring holes and fixing inplace through attachment means for assisting in attachment of the firstportion to the femoral condyle.
 30. The method as recited in claim 29,wherein the attachment means comprises a combination of a plurality ofraised portions with a material selected from the group consisting ofcements, porous bone ingrowth techniques, and polymethyl methacrylate.31. The method as recited in claim 29, wherein the attachment meanscomprises polymethyl methacrylate.
 32. A method of repairing a patient'sdamaged knee, comprising: a step for obtaining a component comprising afirst portion adapted for fixable attachment to a surface a patient'sknee and a second portion adapted with an elongated bearing surfaceadapted to cover a portion of the surface of the patient's knee betweenan anterior portion and a posterior portion of the surface of thepatient's knee; a step for removing a portion of the patient's kneethrough one or more portals to create one or more anchoring holes whilepreserving substantially all other portions of the patient's knee andboth cruciate ligaments; and a step for fixing said component within oneof said one or more anchoring holes such that a portion of said bearingsurface extends above said distal end of the surface of the patientknee.
 33. A method as recited in claim 32, further comprising: a stepfor obtaining a tibial component having a first surface adapted tocooperate with a surface of a tibia and a second surface adapted tocooperate with said bearing surface of said femoral component; a stepfor removing a portion of said tibia to create a channel to receive saidtibial component; and a step for fixing said tibial component withinsaid channel such that said second surface cooperates with said bearingsurface to substantially separate said distal end of said femur fromsaid tibia.
 34. The method as recited in claim 32, further comprising astep for creating one or more portals that are minimally invasive to thepatient.
 35. The method as recited in claim 34, wherein the step forremoving step comprises drilling said anchoring holes in said patient'sfemur with a surgical drill through at least one of said one or moreportals.
 36. The method as recited in claim 35, wherein said step forfixing the femoral component comprises cementing said first portion ofsaid femoral component into one of said one or more anchoring holes. 37.The method as recited in claim 36, wherein the step for fixing femoralcomponent comprises a step for attaching said first portion by way ofpolymethyl methacrylate.
 38. The method as recited in claim 33, whereinthe step for removing comprising a step for sawing and chiseling aportion of said patient's tibia through one or more portals created inthe patient's knee.
 39. The method as recited in claim 38, wherein thestep for fixing tibial component comprises a step for attaching saidfirst surface to said tibia by way of polymethyl methacrylate.